Setting up a surveillance system for sexually transmitted diseases in the general population with prospective data collection from private-practice and public-practice doctors in Hong Kong

Accurate surveillance data on sexually transmitted diseases (STD) is crucial for the prevention, treatment and control of such diseases [1]. However, most of the current STD surveillance studies focus only on specific high risk groups [2], since population-based surveys are expensive and difficult to implement [3]. In many countries, case reporting remains the mainstay of surveillance on STD [4] and does not include data obtained from patients of private patients. In the United Kingdom, Italy and Portugal, only those STD cases seen by public-practice physicians need to be notified [4, 5]. In mainland China, surveillance of STD relies solely on mandatory case-reporting data obtained from government facilities [5]. There is a need to improve the coverage - and hence the effectiveness - of the STD surveillance system [4]. Similarly in Hong Kong, surveillance data on STD are based on data reported by the Social Hygiene Clinics (SHC) of the Department of Health and patients who seek STD-related consultation from private-practice physicians are excluded from the surveillance system. In 2008, 13,867 STD cases were diagnosed in the SHC [6]. The ratio of STD cases being identified by local public-practice versus private-practice doctors remains unknown.

This study tested the feasibility of setting up a surveillance system for STD in the Hong Kong general population by projecting the number of STD cases presented to private-practice and public-practice doctors within a specific 15-day study period, in order to estimate territory-wide STD figures. The prevalence of STD and reproductive tract infection (RTI) syndromes among patients seeking consultations from three types of private-practice doctors, i.e., general practitioners (GP), obstetric and gynaecology (O&G) doctors and dermatologists/venerologists (D&V), and doctors of the public SHC, was estimated. Previous surveys revealed that these three types of doctors provided treatment for over 90% of the STD/RTI cases in Hong Kong [7, 8]. The total numbers of patients presenting STD/RTI syndromes respectively to private-practice and public-practice doctors were projected. The ratio of such patients seen by the two types of doctors was calculated. In addition, the prevalence of all Hong Kong adults presenting STD/RTI syndromes to the two types of doctors during the study period was estimated.

The study demonstrated the feasibility of setting up an improved STD/RTI surveillance system based on the number of cases being diagnosed by private-practice and public-practice doctors in Hong Kong over a defined time period. The process evaluation results are encouraging. It is hence possible to create a stable cohort of participating doctors, allowing the Department of Health to trace the prevalence of STD/RTI in the general population. The results obtained from this study can be used as baseline data for future surveillance studies using the same methodology.

In countries such as the United Kingdom, Italy, China and Portugal, surveillance of STD are still dependent on reporting of cases via government channels [4, 5]. Our study demonstrated that such surveillance systems might provide incomplete or even inaccurate STD data, as private and public patients have rather different socio-demographic characteristics and presented different types of syndromes during the clinical visit. Only two out of nine patients presenting STD/RTI syndromes sought consultation from public-practice doctors: however, the ratio varied from 1:1 for genital growth to 14:1 for urethral/vaginal discharge (i.e. those with urethral/vaginal discharge were quite unlikely to see public-practice doctors). Case-reporting from government medical services alone is inadequate to form an adequate STD surveillance system.

It is projected that, within the 15-day study period, about 12,504 adult STD/RTI cases were presented to all private-practice or public-practice doctors in Hong Kong. The estimated prevalence of adult STD/RTI diagnosed by all private-practice and public-practice doctors during the study period was 0.22%. It must be understood that this figure is not the prevalence of STD/RTI among adults in Hong Kong; asymptomatic STD/RTI cases such as Chlamydia were not included in the numerator. The figure could at best be seen as a lower limit of the prevalence of STD/RTI. The purpose of this study was, instead, to establish a viable surveillance system that can capture changes over time.

In this study, the sex ratio of patients presenting STI/RTI syndromes in public SHC was much lower than that of the private patients; 55.7% and 72.1% of the patients with urethral/vaginal discharge were females in the public and private clinics respectively. The observed contrast might be explained by differing health-seeking behaviors by gender. Women are significantly less likely to seek treatment from public hospitals or genital-urinary medical clinics [12‐14]. The higher level of stigmatization associated with women contracting STD might compromise their access to information and power of decision on seeking health care, as compared to their male counterparts [14, 15]. Females might also perceive stronger stigmatisation when presenting STI/RTI syndromes to public-practice doctors; they may therefore resort to private-practice doctors, who may be able to offer a better sense of privacy and confidentiality and hence a low degree of stigmatisation. Potential obstacles to females in utilizing public STD services should be reviewed and be rectified, as women who could not afford private services may have their STI/RTI syndromes untreated, or may utilize over-the-counter medicine to treat such problems [12].

The fact that the majority of the STI/RTI cases presented to public-practice doctors were male may lead to a misconception that STI/RTI in Hong Kong is essentially a problem of the male, which is not true. It is observed that, although males were more likely than females to present genital growth, ectoparasitic infestations and other syndromes to private-practice and public-practice doctors, the reverse was true for syndromes including urethral/vaginal discharge and genital ulcer. Overall, males have a higher prevalence of STD/RTI than females, but the difference was only moderate (0.26% versus 0.18%). Taking private-practice and public-practice doctors' cases into account, a very different conclusion about sex differentials would be made, as compared to that based only on private-practice doctors' data.

The response rates of the O&G and D&V doctors were low. Provision of a higher monetary incentive and collaborations with the professional associations might improve the response rates. According to the projected number, about 4% of the O&G doctors' patients presented some STD/RTI syndromes to their doctors. These doctors should therefore be involved regularly in safer sex promotion campaigns. This is especially relevant to female patients, who are much less likely than males to make use of public STD services. It is seen that 70.8% of all STD patients that were captured from this study came from the GP. It is therefore important for public-practice health workers to develop partnerships with private-practice doctors and to strengthen health promotion for HIV/STD prevention in the primary care environment.

The study has several limitations: First, despite multiple means of providing incentives to participate in the study, the overall response rate for the three types of private-practice doctors was only 26%. We therefore have to assume that there was no difference between the numbers of STD/RTI patients seen by doctors who did and did not participate in the study. Although the geographical locations and genders of the participating doctors were comparable to those doctors who declined to participate, this assumption could still be invalid. Other information, such as the sizes of clinics, was not available for comparison. The direction of the potential bias is unknown. Second, only three categories of private-practice doctors were included in this study. Other specialists may also have provided care to STD/RTI cases during the study period, although it is expected that such numbers would be relatively small. Third, the study period was short and the choice of timing was arbitrary; the results may be biased by seasonal effects. Fourth, several studies demonstrated that a large proportion of patients used self-medication rather than licensed health facilities to treat their STD syndromes and these cases were not covered by this study [12, 16, 17]. Increase in this form of health service-seeking behavior among STD patients may therefore confound observed trends. Additionally, asymptomatic cases were also not included in this study; the size of such population is unknown. However, the proposed study design may be acceptable from a surveillance perspective, as the method would still be able to detect differences and trends, even though the level may have been shifted by some biases, assuming the biases and the pattern of health-seeking behaviors among STI/RTI patients remain rather stable over time. Lastly, data were self-reported by the doctors and issues surrounding accuracy of information may exist. Validation of such data was not feasible.

In summary, despite the aforementioned limitations, our study offers a viable and pioneering approach for setting up a surveillance system by including data from both private and public practitioners. The private-practice doctors found this system acceptable to them. The data have important policy implications for STD prevention and control in Hong Kong. It is necessary that private-practice doctors participate in STD/RTI surveillance and contribute to HIV/STD prevention. The public STD services should also cater for the gender-specific needs of patients.